김선주 Kim Sun Joo , 김필식 Kim Phil Shik , 임창영 Lim Chang Young

DOI: JKWST Vol.46(No.1) 3-13, 2004

---

For optimal irrigation reservoir operation during flood and normal period, a general and systematic policy is suggested to make balance of the conflicting purposes between water conservation and flood control. We developed Open Water Management Program (OWMP) with an open architecture to deal with newly arising upgrade problems for optimal management of irrigation reservoir. And we evaluated the applicability of OWMP to estimate daily runoff from an agricultural watershed including irrigation reservoirs, and analyzed behaviour of irrigation reservoirs as irrigation water requirements considering frequency analysis of reservoir storage and frequency analysis water requirements for effective management of reservoir. When we executed OWMP with data produced from an experimental field, IHP basins, the mean relative errors of application of daily runoff and irrigation water requirement were less than 5%. We also applied OWMP to a Seongju irrigation reservoir to simulate daily runoff, storage and water requirement from 1998 to 2002, and the mean model efficiency between measured and simulated value was 0.76. Our results based on the magnitude of relative errors and model efficiency of the model simulation indicate that the OWMP can be a tool nicely adapted to the effective water management of irrigation reservoir for beneficial water use and flood disaster management.

권형중 Kwon Hyung Joong , 신사철 Shin Sha Chul , 김성준 Kim Seong Joon

DOI: JKWST Vol.46(No.1) 15-24, 2004

---

The purpose of this study is to estimate monthly evapotranspiration (ET) using normalized difference vegetation index (NDVI) obtained from NOAA-AVHRR data sets. Actual evapotranspiration was evaluated by the complementary relationship, and monthly NDVI was obtained by maximum value composite method from daily NDVI images in the Korean peninsula for the year 2001. The monthly actual ETs for each land cover were compared with the monthly NDVIs to determine relationships between actual ET and NDVI for each land cover category. There was a high correlation between monthly NDVI and monthly mean actual ET. This study presents an alternative approach for land surface evapotranspiration based on remote sensing techniques.

이성행 Lee Seong Haeng

DOI: JKWST Vol.46(No.1) 27-34, 2004

---

A model test is carried out to investigate flow-induced vibration of a Tainter gate in estuary sulices. The gate model scaled with the ratio of 1:25 is made of acryl panel dimensioned 0.66m in width, 0.5m in height in the concrete test flume. Firstly, natural frequencies of the model gate are measured and the results are compared with the numerical results in order to verify the model. The amplitudes of the vibration are measured under the different gate opening and water level conditions in flow from the gate outside to the gate inside. Also 5 revised gate models with bottom width increased 0.5 cm each are tested under the different gate opening and water level. The results are analyzed to study the characteristics of the gate vibration. These test results are assessed in comparison with formerly test results, as a result, presents a design method of Tainter gate to reduce the gate vibration and a basic data for the guide manuals of gate management.

성찬용 Sung Chan Yong , 김영익 Kim Young Ik

DOI: JKWST Vol.46(No.1) 35-40, 2004

---

This study is performed to examine the physical and mechanical properties of eco-concrete using soil, natural coarse aggregate, excellent soil compound and polypropylene fiber. The test result shows that mass loss ratio is decreased with increasing the content of coarse aggregate and excellent soil compound. The compressive and flexural strengths are increased with increasing the content of coarse aggregate, excellent soil compound and polypropylene fiber. The coefficient of permeability is decreased with increasing the content of coarse aggregate and excellent soil compound, but it is increased in 0.2% polypropylene fiber content. The lowest coefficient of permeability is showed in 5.066×10^-9cm/s. These eco-concrete can be used for farm road.

박찬기 Chan-gi Park , 원종필 Jong-pil Won

DOI: JKWST Vol.46(No.1) 41-51, 2004

---

FRP re-bar in concrete structures could be used as a substitute of steel re-bars for that cases in which aggressive environment produce high steel corrosion, or lightweight is an important design factor, or transportation cost increase significantly with the weight of the materials. But FRP fibers have only linearly elastic stress-strain behavior; whereas, steel re-bar has linear elastic behavior up to the yield point followed by large plastic deformation and strain hardening. Thus, the current FRP re-bars are not suitable concrete reinforcement where a large amount of plastic deformation prior to collapse is required. The main objectives of this study in to evaluate the tensile behavior and the fracture mode of hybrid FRP re-bar. Fracture mode of hybrid FRP re-bar is unique. The only feature common to the failure of the hybrid FRP re-bars and the composite is the random fiber fracture and multilevel fracture of sleeve fibers, and the resin laceration behavior in both the sleeve and the core areas. Also, the result of the tensile and interlaminar shear stress test results of hybrid FRP re-bar can provide its excellent tensile strength-strain and interlaminar stress-strain behavior.

원종필 Won Jong Pil , 윤종환 Yoon Jong Hwan , 김완영 Kim Wan Young

DOI: JKWST Vol.46(No.1) 53-60, 2004

---

Roller-compacted concrete(RCC) dam have gained acceptance worldwide in a relatively short time due to their low cost, which is derived in part from their rapid method of construction. And RCC has recently emerged as an economically attractive material for dam construction, replacing the use of conventional concrete and even challenging the economics of earthfill and rockfill embankment dams. There are existing two major mix design methods, one used in USA and the other used in Japan. In this study, proper mix proportions of concrete for RCC dam is obtained using method of compound their merit.

민정기 Min Jeong Ki , 김영익 Kim Young Ik

DOI: JKWST Vol.46(No.1) 61-71, 2004

---

The performance evaluation and deflection of 3 spans concrete simplicity slab bridge analyzed by non-destructive and loading test. Compressive strength of slab and pier appeared in the range of each 353∼366 kgf/cm² and 152∼215 kgf/cm² in rebound number test. Also, it appeared that concrete quality of slab was good after performance improvement. The average compressive strength of slab by core picking appeared 229 kgf/cm². In reinforcing bar arrangement test of span and member, it appeared that horizontal and vertical reinforcing bar was arranged to fixed interval. The value of calculation deflection that carried structural analysis with deflection analysis wave in static loading test appeared higher than that of experimental deflection and it appeared that hardness of this bridge was good. Maximum impact factor that estimated from deflection by running speed in dynamic loading test appeared by 0.216 in 10 km/hr running speed.

강문성 Kang Moon Seong , 박승우 Park Seung Woo , 김상민 Kim Sang Min , 성충현 Seong Chung Hyun

DOI: JKWST Vol.46(No.1) 75-86, 2004

---

The objective of the research is to develop agricultural resue technologies of reclaiming the effluents from a municipal wastewater treatment plant and reusing for irrigated rice paddies. The Suwon wastewater treatment plant was selected for wastewater reuse tests. The control was the plots with groundwater irrigation (TR#1), the treatment (TR#2) using polluted stream water as it was, and three others using wastewater after treatment. Three levels of wastewater treatments were employed: the effluent from the wastewater treatment plant TR#3), sand filtering after treatment plant(TR#4), and ultra-violet treatment after sand filtering (TR#5). The randomized block method was applied to wastewater application to paddy rice with five treatments and six replica. The effects of various wastewater treatment levels on water quality, paddy soil, crop growth, yields, and the health hazards were investigated. The primary results indicate that cultivating rice with reclaimed wastewater irrigation did not cause a problem to adverse effects on crop growth and yields. Overall, wastewater could be used as a practical alternative measure for reclaimed wastewater irrigation. However, long-term monitoring is recommended on the effects on soil chemical characteristics and its related health concerns.

강민구 Kang Min Goo , 박승우 Park Seung Woo , 손정호 Son Jung Ho , 강문성 Kang Moon Seong

DOI: JKWST Vol.46(No.1) 87-97, 2004

---

The paper presents the results from the applications of the Water Erosion Prediction Project (WEPP) model to a single plot, and also a small watershed in the Mid Korean Peninsula which is comprised of hillslopes and channels along the water courses. Field monitoring was carried out to obtain total runoff, peak runoff and sediment yield data from research sites. For the plot of 0.63 ha in size, cultivated with corn, the relative error of the simulated total runoff, peak runoff rates, and sediment yields using WEPP ranged from -16.6 to 22%, from -15.6 to 6.0%, and from 23.9 to 356.4% compared to the observed data, respectively. The relative errors for the upland watershed of 5.14 ha ranged from -0.7 to 11.1 % for the total runoff, from -6.6 to 35.0 % for the sediment yields. The simulation results seem to justify that WEPP is applicable to the Korean dry croplands if the parameters are correctly defined. The results from WEPP applications showed that the major source areas contributing sediment yield most are downstream parts of the watershed where runoff concentrated. It was suggested that cultural practice be managed in such a way that the soil surface could be fully covered by crop during rainy season to minimize sediment yield. And also, best management practices were recommended based on WEPP simulations.

최선화 Choi Sun Hwa , 김호일 Kim Ho Il , 김민호 Kim Min Ho , 이변우 Lee Byun Woo , 이봉훈 Lee Bong Hun

DOI: JKWST Vol.46(No.1) 99-105, 2004

---

The present agricultural water quality standards are set by a policy goal. This is intended for water quality management of public water resources, but not for the use of water resources. These standards were not determined by considering the influence of water quality on the safety of agricultural produce and the growth, yield and quality of agricultural crops. Thus, this study was carried out to investigate the influence of irrigation water quality on the growth, yield, and grain quality of rice and acquire fundamental knowledges to set up irrigation water quality standards. The pot experiment was conducted with 4 treatments using irrigation waters with various total nitrogen concentrations (control, 1, 5, 10, 20㎎/L) and replicated four times with randomized block design. The results of this study showed that plant height, number of tiller, plant dry weight, the uptake of N, P, and K, and rice protein contents tended to increase as the T-N concentration in irrigation water was increased. In addition, grain yield at T-N 20 mg/L was significantly higher than in the control, but the percentage of head rice was slightly lower due to the increase of green kernel and white belly/core kernel.

이광야 Lee Kwang Ya , 엄명철 Eom Myung Chul , 조재원 Cho Jae Won , 정해진 Jeong Hae Jin

DOI: JKWST Vol.46(No.1) 107-117, 2004

---

Hourly monitoring data from Saemangeum estuary, which is expected to become freshwater, was analyzed to evaluate the water quality characteristics. Higher algal growth at spring season than winter influenced the high ratio of organic nitrogen to total nitrogen and concentration of chemical oxygen demand (COD). About 87.9% and 59.7% of organic nitrogen was observed at winter season and spring season, respectively. Daily salinity analysis at the mouth of two main rivers demonstrated that the Dongjin river was more influenced by tidal effect and showed higher variation than the Mankyung river. The ratio of nitrogen to phosphorus (N/P ratio) was different with site (estuary versus sea area) and season (winter versus spring) remarkably. The N/P ratio was highest (32.74 ~ 43.93) at estuary in winter and was lowest (1.78 ~ 3.06) at sea in spring. The high N/P ratio at estuary area implies that phosphorus can be the limiting nutrient factor for algal growth as in general freshwater river, therefore, water quality management practice considering river characteristics rather might be needed in the Saemangeum estuary. The Saemangeum project is nationally recognized for its environmental issues, and especially water quality concern is a critical factor to make policy decision and further assessment with continued monitoring is strongly recommended.

서교 Suh Kyo , 이정재 Lee Jeong-jae , 허유만 Huh Yoo-man , 김한중 Kim Han-joong , 이호재 Yi Ho-jae

DOI: JKWST Vol.46(No.1) 121-131, 2004

---

Transportation and logistics of agricultural products have been one of the major interests of many researches. Most of researches have been limited to presuming these as a first dimensional process or considering only economic value of agricultural products at each stage of logistics. However, the particular characteristics of agricultural products, such as quality change during transportation or extensively scattered origins, require examining these problems as a whole system. Network model has been adopted to represent nodes, which stand for spatial location of demand and supply of agricultural products, and communication between these nodes. Based on network theory and advanced marketing potential function, an optimal routes selection model is developed. The model employed network simplex method for routes optimization. The application of the model focused on transportation network organization to reflect different market prices for different locations and resulted in optimum routes and profit improvement of the applied agricultural product.